Get the car real level and drain the tranny lube into a clean container.
Do check the vent.
Repack the CV joint.
The best thing to use on the flange caps is Permatex #2A , or it might just be called #2 now. But its dark brown gooey sticky as heck, and non-hardening. Get them completely degreased and dried out good before applying the #2A and re-installing.
Then refill with the tranny lubricant using 1.5 quarts.